The application relates to a rectifier circuit with at least one field effect transistor which includes a control electrode and two switching electrodes. The control electrode thereby operates the field effect transistor from a reverse state to an opening state and vice versa between the two switching electrodes and vice versa. The rectifier circuit furthermore includes one driver which cooperates with a voltage sensor of the field effect transistor and which operates this to the forward state with the diode operating state of the field effect transistor.
During the switching from the reverse state into the forward state, a residual voltage remains in the diode operation, which voltage can lead to large forward losses with synchronous rectifier circuits. It is therefore necessary to provide at least one field effect transistor which switches to the forward state in a timely manner. However, this requires a measuring technique which signals a driver of the field effect transistor in a timely manner that it shall connect and pass from the diode forward operation to the channel conducting state. However, in this transition phase, voltage peaks paired with very high voltage and current changes per time unit dv/dt and di/dt can occur, which are a multiple of the voltage to be realized in the diode forward operation.
During a measurement of the voltage in the diode opening operation between source and drain by using an integrated circuit, the integrated measuring circuit thus has to have a high electrical strength at the inlet, so that it can recognize the diode opening operation safely despite high voltage peaks and is protected against overvoltage peaks.
Another solution consists in cutting the high voltage part at the drain of a field effect transistor via a diode, so that the input for the integrated measuring circuit is drawn to a reference potential. But as soon as the voltage drops below 5 V, the diode becomes conducting, so that it is possible to use an integrated measuring circuit with an input with a low electrical strength, so as to detect the voltage in the diode opening operation at such a field effect transistor in a timely manner.
However, the last-mentioned possibility requires additional components as for example diodes, so as to ensure that the integrated circuit is protected from occurring voltage peaks. The known possibilities are thus cost-intensive solutions which require a complex circuit on the one hand and result in a restriction of the lift of the wanted signal for the voltage sensor.
For these and other reasons, there is a need for the present invention.